bootctl: do not fail on removing unfied kernel image

A boot loader entry for a unified kernel image has
BootEntry.kernel : path to the image relative to ESP or XBOOTLDR,
BootEntry.path   : path to the image.
Hence, these two effectively point to the same file.

Hence, by unlink command, the image is removed by
```
deref_unlink_file(&known_files, e->kernel, e->root);
```
then later tried again by
```
r = chase_and_unlink(e->path, root, ...);
```
and of course it fails with -ENOENT.

Let's ignore the failure there. We already ignore ENOENT on removal
at various places, especially in deref_unlink_file().

Fixes #38706.
Follow-ups for 8702496bfb.

src/bootctl/bootctl-status.c

@@ -781,7 +781,7 @@ static int unlink_entry(const BootConfig *config, const char *root, const char *
 
         r = boot_config_find_in(config, root, id);
         if (r < 0)
-                return r;
+                return 0; /* There is nothing to remove. */
 
         if (r == config->default_entry)
                 log_warning("%s is the default boot entry", id);
@@ -802,6 +802,8 @@ static int unlink_entry(const BootConfig *config, const char *root, const char *
                 log_info("Would remove \"%s\"", e->path);
         else {
                 r = chase_and_unlink(e->path, root, CHASE_PROHIBIT_SYMLINKS|CHASE_TRIGGER_AUTOFS, 0, NULL);
+                if (r == -ENOENT)
+                        return 0; /* Already removed? */
                 if (r < 0)
                         return log_error_errno(r, "Failed to remove \"%s\": %m", e->path);
 
@@ -833,7 +835,8 @@ static int list_remove_orphaned_file(
         if (arg_dry_run)
                 log_info("Would remove %s", path);
         else if (unlinkat(dir_fd, de->d_name, 0) < 0)
-                log_warning_errno(errno, "Failed to remove \"%s\", ignoring: %m", path);
+                log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno,
+                               "Failed to remove \"%s\", ignoring: %m", path);
         else
                 log_info("Removed %s", path);
 
@@ -920,12 +923,9 @@ int verb_list(int argc, char *argv[], void *userdata) {
                 return cleanup_orphaned_files(&config, arg_esp_path);
         } else {
                 assert(streq(argv[0], "unlink"));
-                if (arg_xbootldr_path && xbootldr_devid != esp_devid) {
+                if (arg_xbootldr_path && xbootldr_devid != esp_devid)
                         r = unlink_entry(&config, arg_xbootldr_path, argv[1]);
-                        if (r == 0 || r != -ENOENT)
-                                return r;
-                }
-                return unlink_entry(&config, arg_esp_path, argv[1]);
+                return RET_GATHER(r, unlink_entry(&config, arg_esp_path, argv[1]));
         }
 }